Abstract

Located on the southern flank of the Paradox basin, the White Mesa field (with one exception) produces from the Desert Creek zone of Pennsylvanian (Cherokee) age. To Dec. 1, 1958, there were 48 oil wells. Structurally the area can be divided into 2 units. The southeastern part strikes N30 degrees W-N90 degrees E, and dips gently W and N at approximately 60-115 ft. per mi. It is probable that this part is the W and N flanks of an anticline located E and SE of present wells. In the northwestern part of the field, a small area of "closure" is present. This part trends NW-SE, and is related to the Ratherford field NW of White Mesa. It is separated from the southeastern part of White Mesa by a narrow syncline opening(?) NE. Stratigraphically the field is an area of rapid lateral and vertical lithologic change. Broadly it can be divided into 3 units: high-carbonate (more than 79%) rocks on the northern margin; high-carbonate rocks trending N-S, subsidiary to the northern unit; and a restricted lithofacies bordering the northern margin and surrounding the N-trending carbonate lithofacies. Because of these variations oil has been environmentally trapped. The specific change, most instrumental in entrapment, is the transition from deposits of a shallow, well-oxygenated, agitated, marine environment to deposits of a deeper-water, relatively quiet, restricted, marine environment. The latter might be called "lagoonal. " Many wells in White Mesa produce from rocks deposited in the restricted environment; 11 dry holes have found a slightly greater environmental restriction and were not productive due to negligible permeability. In origin, White Mesa and the related fields (Aneth, McElmo Creek, Ratherford) have been called a "reef complex." The writer believes the term biostromal complex to be more descriptive of Desert Creek zone stratigraphy in the area.